Protective device for electric circuits.



PATENTED JUNE 9, 1908.

v H. W. CHENEY. PROTECTIVE DEVICE FOR ELECTRIC CIRCUITS- APPLIOATION FILED APR. 29, 1907.

mm mm 3 wa' ,3 w@

UNITED STATES PATENT OFFICE.-

HERBERT W. GHENEY,'OF NORWOOD, OHIO, ASSIGNOR TO ALLIS-OHALMERS COMPANY, A CORPORATION OF NEW JERSEY, ANDTHE BULLOCK ELECTRIC MANUFACTURING COM- PANY, A CORPORATION OF OHIO.

PROTECTIVE DEVICE FOR ELECTRIC 'GIRGUITS.

No'i 890,496.

Specification of Letters Patent.

Patented J'une.9, 1908.

Application filed April 29, 1907. Serial No. 370,959.

To all whom it may concern:

Be it known that I, HERBERT W. OHENnY,

' citizen of the United States, residing at Norwood, 1n the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Protective Devices for Electric Circuits, of which the following is a full, clear, and exact specification.

My invention relates to protective devices 1011forelectric circuits, particularly as-used in x :tfiinjunction with motor starters;

s As electric motors require more current to start them than to maintain them atnormal speed,- a protective device which properly protects a motor'when at normal speed does not permit suflicient current to pass for startpermits the passage pf to the same objection.

The object of my invention is to providea rotectivedevice in conjunction with a start- 1ng controller which shall pro ,erly protect a" evice at, both starting and during normal operation while ,also allowing the heavy current necessary for motor or other translating starting.

nyention, therefore COIIlPII SGS' the com nationof a translating dev1ce, a con- I troller therefor, and a protective device for said translating device arranged to carry different currents in proportion to the total current supplied when the controller is in different positions. Rather more specifically my invention comprises the combination of an electric motor, a starting controller therefor, a plurality of fuses, v and connections whereby the controller when in a starting position comletes the circuit through said fuses in paralel, and when in running position cuts out part of said parallel-connected fuses.

Other features of my invention will appear from the description and drawings and Wlllbe particularly pointed out in the claims.

Figure 1 shows a development of a starting controller embodying my invention, the motor and the electrical connections being shown diagrammatically; Figs. 2 and 3 show simple connection diagrams for the starting and running positions of the controller re spectively.

The duplicate halves of the controller drum A co-act respectively with the two sets of diametrically opposite contact fingers 10 and 11 during one complete operation of the i controller and with'the opposite sets during I the next complete operation thereof. The

normal operation of the controller is always the running to the off position. Such a controller has duplicate off, starting and running positions. In the controller shown there is ut one startingposition between the off and running positions, but obviously there may be any desired number of such starting posi tions. The structural details of the starting controller form no'part of my present invention and are unnecessary to an understanding thereof.

When the controller is in a starting position S, the auto-transformer windings 12 and 12? are respectively connected between the mains f andg, and g and h, of a three-phase supply system, and the three terminals of the three-phase induction motor M are respectivelyconnected to the common terminal of the two auto-transformer windings and'to an intermediate point on each of said windings 12 and12 thus constitute in effect a single V-connected auto-transformer, the main g and one terminal of the motor being connected to the middle of the V.

In the connection between the main'g and the common terminal of the two auto-transformer windings is the fuse 15,. while the other terminals of the transformer windings are respectively connected to the mains f and it through two smaller parallel-connected fuses 13 and 14, and16 and 17-. Variable resistances 18, 19, 2-0 and 21 are in series with the fuses L3, 14, 16 and 17 respectively to vary the relative current strengths in the prallel-connected fuses, to render these current strengths more nearly independentof variations of resistance in different fuses which may be used from time to time, and to provide means for correcting for any slight variation in such resistance which may occur;

l/Vhen the controller is in running position R, the auto-transformer windings i=2 and 12 the same direction to avoid passing through the starting position in moving from and the fuses 13 and 17 are disconnected, and the motor terminals are connected to the three mains through the fuses 14, 15-and 16 respectively. 7 Thus when the controller is in a starting position a heavy current may be drawnfrom the line, because the fuses 13 and 17 help the fuses 14 and 16 to carry such current.

current. This allows sufficient currentfor starting the motor, the fuse 15 being prefer .whether the controller is in starting or running position, while sufficient current can be obtained for starting the motor.

In manyinstances-theresistances 18, 19,

2t) and 21' be dispensed with. In other instances the'fuses 13 and 17 and the resistances 19 and 20 may be dispensed with, the resistances'18 and-21 taking the place of the fuses 13 and 17 and diminishing the proportional'current taken by the fuses 14 and 16 when the controller is in a starting position.

" Moreover the fuse 15 is not always necessary.

Although I have described my invention as applied to a potential starter for three- .phase induction motors, it is equally applicable to any other type of starting controller for any kind of motors and for other translating devices than motors. Many other changes may be made in the precise arrangemehts here shown and described, and all such which do not involve a departure from the spirit and scope of my invention, I aim to cover in the following claims.

What I claim as new is 1. In combination, a translating device, a controller therefor, and a fuse for protecting said translating device and arranged to carry different currents in proportion to the total current supplied when the controller is in difierent positions. v

2. In comb1nat1on,=an electric motor, a

starting controller therefor, and a protective device for said motor arranged to carry different currents in pro ortion to the total current supplied when t e controller is in starting and running positions. 3. In combination, an electric motor, a fuse in the supply circuit therefor, and a starting control er for the motor arranged when in a starting position, and then only to shunt a part of the current around the fuse.

4. In combination, an electric motor, a fuse in the supply circuit therefor, and a controller for the motor arranged to vary the potential impressed thereon and in its different positions to make or break a shunt around said fuse. v

5./In combination an electric motor, a

as starting controller therefor, ,a plurality of when inrunning position cuts out part of said parallel-connected, fuses.

6. The combinat on of a translating de- .vice, a controller therefor, and a protective device arrangedto carry art of the current supplied when the contro ler is in a starting position, and all of the current supplied when the controller is in running position. v

7 In combination, an electric motor, two fuses, and a starting controller for the motor arranged when in a starting position to connect said two fuses in parallel in the motor supply circuit, and when in running position to cut out one of said fuses.

8. In combination, an'electric motor, two fuses, and a starting controller for the motor arranged when in one position to connect said two fuses in parallel in the motor supply circuit, and when in another position to cut out one of said fuses.

' 9. In combination, an electric motor, two fuses, a starting controller for the motor arranged when in a starting position to conto cut outone of said fuses, and a variable resistance in the circuit of each of said fuses.' 11. In combination, an electric motor, a fuse in the supply circuit thereof, a resistance, and a starting controller for the motor arranged when in a starting position to connect said resistance in shunt to said fuse.

12. In combination, an electric motor, a fuse in the supply circuit'thereof, a variable resistance, and a starting controller for the motor arranged when in one position to connect said resistance in shunt to said fuse.

18. In combination, an induction motor, auto-transformer windings, a plurality of fuses, and a starting controller for the motor arranged when instarting position to connect the motor to the supply circuit through said fuses in parallel and through said autotransformer windings, and when in running position to connect thernotor directly to the supply circuit through less than all of said fuses.

14. In combination, an induction motor, auto-transformer windings, a plurality -of fuses, and a starting controller for the motor or through saidaute-transformer windings,

means for connecting said cut-outs in parallel in the supplycircuit of the motor and for then-disconnecting one of said cut-outs.

.Correcti'ot in Letters Patent Ne. 890,496,;

16. The combination with an electric motor, of a plurality of thermal cut-outs, and a switch separate from said cut-outs and arranged to connect said cut-outs in parallel in the motor supply circuit and then to dis-, connect part of said cut-outs.

17. In combination, a' translating device,

a plurality of fuses, and a switch separate. from said fuses for connecting said 'translatof the ease in the Patent'Oflice.

[sun] Signed and sealed this 4th day of Au us a. 11,1908.

ing device to a supply circuit first throughsa d fuses in parallel and then through less than all of said fuses.

18. The combination of a translating de- Vice, a. plurality of fuses, and a switch separate from said fuses and arranged to connect said motor to' a supply circuit first through said fuses in such -a manner that each fuse takes but part'of the current and then so that one ,of the fuses carries more of the current.

' .In testimony whereof-I aflix my signature,

.inthe presence of two witnesses.

HERBERT W. CHENEY; Witnesses:

GEO. B. SoHLEY, FRED J .-K1NsEY.

It is hereby certified that in Letters Patent No. 890,496, granted June 9, 1908, upon the application of Herbert Cheney, of Norwood, Ohio, for an improvement in Protective Devices for Electric Circuits, an error appears in the printed specification requiring correction, as follows; In lines 82-83, page 1, after the word windingsfi a period and. the words The windings should be inserted and that the said Letters Patent should. be read withthis correction therein that the same may conform to the record C. C. BILLINGS,

Acting Commissioner of Patents. 

